Wichita eagle. [volume] (Wichita, Kan.) 1886-1890, 1887-06-23
FOREST AND RAINFALL.
IMPORTANT ACTIONS WHICH AFFECT
LAND AND SEA.

|
The First Result When Land is Desti.
tute of Forests-Another Important
| Result-Beautiful Phenomena-Erosion
| of the Soil.
The tangle Of decayed vegetation which
| covers the ground beneath the forest is Of
considerable thickness. On top it consists al
| together of the decayed trunks, branches and
| leaves, but it shades downward into ordinary
| dark colored soil at the depth Of a few feet
| from the surface. This, the decay zone of
the forest, lies between the boughs of the air
and the branches of the roots. In it go on
! the most important actions which take place
in our forests-actions which affect the his
| tory Of land and sea We shall therefore
have to consider it in a somewhat painstaking
way.
The most evident effect of this sheet of de-
caying wood, and moss which feeds on the
decay, is on the rainfall Of the region which
it mantles. When, after season of drought,
a copious rain falls on this spongy mass, the
water is for a long time absorbed in the in
terstices, and does not flow to the rivers.
Even in times Of very heavy rain the water
Is slowly yielded to the streams; after dry
period of many weeks this sponge retains q
good share of water. A like amount of rain
falling on titled fields or prairies slips quickly
away to the rivers and thence to the sea. The
first result is that when the land is destitute
of forests it sheds water like house roofs,
breeding floods after every considerable rain,
while in the forests the rain is only slowly
yielded to the streams
ANOTHER IMPORTANT RESULT
A second and less evident result Of the
spongy character Of the forest bed is that. by
hindering the escape Of the rain water to the
rivers, 1t increases the actual rainfall of the
country. To see the nature and importance
Of this action we must turn aside for a mo-
ment to consider the origin of the rain which
falls upon the land. The original source of
this water supply is the sea, which sends into
the lands tolerably regular annual store of
moisture. When this falls as rain or snow,
either Of two things may happen-the water
may go away directly to the sea or it NAV
return to the atmosphere as vapor to be again
preciptated as rain. The chance of its re-
evaporation is determined by the speed with
which it flows to the streams From a tree
less region 1t rapidly escapes; in an extensive
district OF virgin forest it may again and
again pass from earth to air, and from air
to earth.
The columns of vapor, which in times of
summer rain may be seen ascending from
every great wood, afford visible evidence Of
the effect Of forests on rainfall. They also
may show the observer some of the most beau
tful phenomena of atmospheric circulation.
In summer rain shower the air above the
trees becomes much cooler than it is in the re-
cesses below their tents of foliage This
heated air within the woods seeks to rise and
escapes In great columns wherever there is q
wide gap between the branches: as soon as it
attains the cooler level above the moisture is
condensed, and the air, before transparent.
becomes charged with steam. To replace
this ascending air broad current drifts to-
ward the emerging streams of vapor, COM
monty from the higher parts of the forest.
where the air, owing to the elevation Of the
site, is cooler than in the lower levels.
EROSION OF THE SOIL.
This repeated passage CT the moisture from
earth to cloud and from cloud to earth great
ly increases the amount Of force which the
rain applies in its falling drops to the earth's
surface; but the rank vegetation protects the
surface from the erosion which it would
hillsides of the Cumberland mountains. where
the soil lies on declivities of great steepness,
suffer little wear as long as their natural
protection is left to them. But as soon as
they are stripped Of the garment of wood
which has been upon the region ever since, in
the far off ages, they came from the depths of
the sea, they wear with great rapidly. The !
erosion is limited, as long as they are forest |
clad, to the stream beds, and there is hindered
by the innumerable obstacles of the fallen |
trees and entangled driftwood.
The brooks which are strong enough to clear |
their beds and cut into the earth and rock |
are few in number; we may often, on the |
fatter ground, find tracts of square mile or |
more in area in which there is not single |
stream that ever assails the surface of the |
earth. As soon, however, as the forest mat |
is removed, the surface becomes scanned with |
they often, on the deforested sur
face, increase 100 fold in their length and |
more than that measure in their destructive |
power. Relieved of all restraint from fallen |
timber, or the close knit roots which enmesh |
the earth, they sweep the precious soil away
toward the sea. In single day titled field |
may lose from its surface more soil than
would be taken from it in a century of its
forest state.-Scribner's Magazine.